A so-called flow rack system customarily comprises a series of columns between which are mounted a pair of inclined rails extending between a higher level loading station and a lower level unloading station. Loaded pallets are placed in the rack at the higher level loading station and are withdrawn therefrom at the lower level unloading station after having travelled downwardly on the rails. Various types of speed controllers have been proposed for regulating the speed with which a loaded pallet advances on rails in flow racks.